Reverse transcriptase encoded by a retrotransposon from the trypanosomatid Crithidia fasciculata

Proc Natl Acad Sci U S A. 1991 Nov 1;88(21):9794-8. doi: 10.1073/pnas.88.21.9794.

Abstract

The long interspersed nuclear element (LINE)-like elements are a distinct family of eukaryotic transposons that contain a long open reading frame with limited sequence homology to retroviral reverse transcriptases. Unlike many retrotransposons, they lack long terminal repeats. The mechanism by which LINE-like elements move within the genomes of their hosts remains speculative. We have used an unusual approach to express and detect enzymatic activities associated with Crithidia retrotransposable element 1 (CRE1), a site-specific LINE-like element found in the insect trypanosomatid Crithidia fasciculata. A chimeric gene fusing the yeast retrotransposon Ty1 and the CRE1 open reading frame is constructed and then overexpressed in yeast. Fusion proteins are packaged into virus-like particles, which can be partially purified and directly analyzed for enzymatic activity. Here we demonstrate that CRE1 encodes an RNA-directed DNA polymerase. These data provide direct biochemical evidence that this widely distributed class of retrotransposons encodes reverse transcriptase and sets the stage for a detailed understanding of the mechanisms involved in LINE-like element transposition.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Crithidia fasciculata / enzymology*
  • Crithidia fasciculata / genetics
  • DNA Mutational Analysis
  • DNA Transposable Elements*
  • Genes
  • Molecular Sequence Data
  • Oligonucleotides / chemistry
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • RNA-Directed DNA Polymerase / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Repetitive Sequences, Nucleic Acid
  • Structure-Activity Relationship

Substances

  • DNA Transposable Elements
  • Oligonucleotides
  • Protozoan Proteins
  • Recombinant Fusion Proteins
  • RNA-Directed DNA Polymerase